1. Field of the Invention
The present invention relates to a hot water storage type hot water supply device equipped with a hot water storage tank connected with a water input pipe and a hot water delivery pipe, and a heat source equipment including a heat exchanger connected to the hot water storage tank via a circulating path and a burner for heating the heat exchanger, in which the water at the lower portion of the hot water storage tank is returned to the upper portion of the hot water storage tank via the heat exchanger by operation of a circulating pump provided at the circulating path.
2. Description of the Related Art
Conventionally, in this type of hot water storage type hot water supply device, there is provided a water temperature detector for detecting the water temperature of the lower portion of the hot water storage tank, and operation of a heat source equipment is carried out in accordance with the temperature detected by the water temperature detector. That is, when the detected temperature of the water temperature detector falls below a preset hot water delivery temperature, the circulating pump is operated as well as the burner of the heat source equipment is ignited, so as to heat the water inside the hot water storage tank by the heat exchanger and circulate the same. Then, when the detected temperature of the water temperature detector elevates to the preset hot water delivery temperature, the burner is extinguished as well as the circulating pump is stopped (refer to, for example, Japanese Patent Publication No. H03-8457 (patent document 1)).
During operation of the heat source equipment, the incinerating amount of the burner is controlled so that the temperature at the outlet of the heat exchanger becomes the preset hot water delivery temperature. However, the temperature of the water flowing into the heat exchanger gradually elevates during operation of the heat source equipment, so that even though the incinerating amount of burner is decreased to its minimal possible incineration, there is a case where the hot water temperature at the outlet of the heat exchanger becomes equal to or above the preset hot water delivery temperature, and that hot water of a high temperature is supplied to the upper portion of the hot water storage tank. And, if the water temperature at the lower portion of the hot water storage tank becomes higher than the preset hot water delivery temperature, the water temperature at the upper portion of the hot water storage tank becomes considerably higher than the preset hot water delivery temperature, resulting in waste of energy.
If the capacity of the circulating pump is upgraded, it is possible to prevent the case where the water temperature at the outlet of the heat exchanger become equal to or more than the preset hot water delivery temperature, by increasing the circulating water amount when the temperature of the water flowing into the heat exchanger elevates. However, this result in inconveniences such as the increase in size and the increase in cost of the circulating pump.